The practice of stepping a conveying line is not new and there are many examples in industry; however, the details of the flow behaviour at the step have not been extensively studied. Three step geometries were modelled: an ‘abrupt’ step and two ‘gradual’ step-up geometries from a pipe bore of 75–100mm. The flow behaviour of a single plug of material passing through these geometries was investigated using the ‘Eulerian’ CFD model from Fluent. Solids volume fractions were recorded at 0.01s time steps at several point locations, and visualised throughout the pipe.